Illustration of Oumuamua. In 2017, astronomers discovered an object in the Solar System which seemed … [+] out of place. Its orbit is highly hyperbolic, not parabolic, which implies it originated outside of the Solar System and is just passing through. The interloper has been named Oumuamua Hawaiian for scout or messenger. Follow-up observations have revealed that Oumuamua is very oddly shaped, like a cigar, more elongated than any known Solar System object. Estimates put its size at 200 x 30 x 30 m, and its rotational period at 8.14 hours. An alternative possibility, however unlikely, has been mentioned in a scientific paper – that the object might actually be an alien spacecraft such as a solar sail (left).
Many astronomers are looking for aliens. Thats why we hear so much about exoplanetsand the more Earth-like they are, the more interesting they become.
Theres also the lavishly-funded $100 million Breakthrough Listen scientific research project has radio astronomers listening for messages from the 1,000,000 closest stars to Earth and the 100 closest galaxies. 
So the idea that our Solar System may be visited by as many as seven interstellar objects each year should fascinate anyone concerned with SETIthe search for extraterrestrial intelligence.
Not that extrasolar objects passing through our Solar System are advanced technology, a wild theory proffered by Professor Avi Loeb about Oumuamua (also known as 1I/2017 U1), the first known interstellar object detected in 2017. 
Oumuamua is not an artificial creation of an advanced civilization, but that doesnt make it un-interesting. Discovered on October 19, 2017 by the Pan-STARRS1 Near-Earth Object survey, Oumuamua challenged astronomers assumptions about how small bodies from another star system would look. It moved too fast to be an asteroid, in fact it was accelerating, it left no trail of debrisso couldnt be an icy cometand it also varied in brightness. 
Does any of that make Oumuamua an alien spacecraft? No, it doesnt. Oumuamua was found as it was leaving the Solar System. It was a spectacular discovery, but it was faint. It was observed only for a short time. We didnt get much data on it. For such a unique object, that was frustrating. After all, missions to other star systems are generations away. 
What data we did get was consistent with a purely natural origin for Oumuamua; it varied in brightness because it was oddly sausage-shaped and spinning, and for the same reason it heated unevenly, which might explain its acceleration. As one paper puts it, Oumuamua is entirely explicable as a fragment expelled from its parent planetary system by gravitational interaction at any time in the history of the galaxy. 
Still, the same scientists that were intrigued by Oumuamuaand in 2018 by another interstellar visitor, the 2l/Borisov rogue cometwould love to get their telescopes on as many visitors from other star systems as possible. 
Cue a paper that uses data from the Gaia satellite to predict that seven fast-moving objects from other star systemlike Oumuamuashould pass within 1 AU (astronomical unit) of the Sun each year. An AU is the distance from the Earth to the Sun. The paper also predicts that interstellar comets like 2I/Borisov could be a once-per-decade eventand that three objects per century could even be from other galaxies.
Oumuamua comet, interstellar object passing through the Solar System, unusual shaped asteroid
All-sky synoptic surveys such as the Vera C. Rubin Observatory are expected to discover several interstellar interlopers per year. However, only if theyre detected earlyfar earlier than Oumuamua wascould such an object be visited by a spacecraft. 
We propose an intercept mission for interesting interstellar interlopers that would be ready to launch in case a target of opportunity presents itself, reads a NASA-sponsored paper published earlier this month about the search for the techno-signatures from alien civilisations. If the target is detected with sufficient lead time, thanks to the new survey facilities, it may be possible to catch it within 20 years.
To catch these terrifically fast-moving objects a spacecraft would have to be launched as the object rounded the Sun. Astronomers would therefore need to spot such an object as it entered the Solar System, something the Vera C. Rubin Observatory may be able to do. 
An Interstellar Sample Return Mission is exactly whats being proposed by USNC, which is currently powering NASAs Perseverance rover on the Martian surface. Awarded a Phase 1 grant from the NASA Innovative Advanced Concepts, its idea is to use a plutonium-powered spacecraft to catch up to an extrasolar object, collect a sample, and return to Earth within a decade. 
Such a mission has the potential to radically change what we know about our place within the Universe. After all, a mission to intercept an interstellar object that passes through our Solar System could yield similar results to interstellar travelsomething that could take many centuries to launch let alone yield results from. 
Sometimes its best to wait for the Universe to come to you. 
Wishing you clear skies and wide eyes.